I interpret that as spins were very much a part of a pilots life in ww1, intentional or not, and that once they learnt how to recover from a spin, well, they recovered...they survived.
You're quite right... except maybe for some plane designs (even today some 3-axes ultralights are known not being able to recover from a spin).
Regarding spins, WWI chronology was:
1916: after a few pilots succeeded (by luck) to exist spin, some test pilots (starting with factory then army test pilots) started to test spins and invented the first recovery procedures late 1916.
1917: in early 1917, some recovery procedures were included in flight manuals, in middel 1917, the spin recovery was part of the standard "first level" stunt training (as shown by FlyRetired)
1918: Spin recovery was quite usual in flight combats End of 1918 saw the first theoretical reports about spin and recovery (allowing to fully understand the procedures and to upgrades them).
This doesn't mean that spin recovery is easy. It's quite tricky (you can easilly stall if you recover to quickly, and thus create another spin), asking for good nerves and a "cool-head" attitude... and regarding spin start and spin recovery, each particular plane type has its own caracteristics that you must learn and master.
